SpaceX founder Elon Musk is “80%-90% confident” that the company’s massive new Starship rocket will reach orbit next year and said there’s a chance it will be ready for an uncrewed cargo mission to Mars in 2024.

The initial test flights will be difficult and carry a high risk of failure, Musk said Friday at a virtual session of the Mars Society’s 2020 conference. “We’ll probably lose a few ships before we get the atmospheric return and landing right,” he said.